A light emitting diode (LED) is a p-n junction diode having a characteristic in which electric energy is converted into light energy, may be produced by combining dopants of semiconductor compounds on the periodic table and may represent various colors of a blue LED, a green LED, an UV LED, or a red LED or the like by adjusting the compositional ratio of the semiconductor compounds.
For example, a red LED may include an AlGaInP-based LED, which may convert the injected electric energy into light having a wavelength in the range of about 570 nm to about 630 nm. The wavelength variation depends on an intensity of band gap energy of the LED, and the intensity of the band gap energy may be adjusted by adjusting a composition ratio of Al and Ga, and the wavelength may be shortened as the compositional ratio of Al is increased.
Meanwhile, recently, an application area of the AlGaInP-based red LEDs has been expanded to a light source for high color rendering index (high CRI) or a light source for a vehicle, and a market competition according thereto is intensifying, and thus ensuring high optical power or electrical reliability has been raised as an important issue.